Electrical components, which include electronic equipment, are often enclosed in a housing suitable for the environment in which the components will operate. Such equipment may operate in applications where the environment is subject to high temperatures, vibration or dust. During operation of electrical components, some of the energy consumed is converted into heat. Electrical component manufacturers specify the temperature range over which electrical components are designed to operate. The operating temperature range should not be exceeded as the electrical components may not operate reliably outside of the specified temperature range or they may fail when operated outside the specified range. Heat-generating electrical equipment includes, but is not limited to, industrial computers, disk drives, power supplies, power converters, audio amplifiers, power amplifiers, personal computers, automotive computers and inverters.
Electrical components in some applications are cooled by a fan that circulates air within the housing. The moving air conducts heat away from hotter electrical components resulting in a more uniform air temperature within the housing. In other applications, air is drawn into the housing through openings in the housing by a fan exhausting heated air from the housing at a location that causes the incoming airflow to pass over electrical components to be cooled before the air is exhausted from the housing.
In other applications, a heat sink is provided for heat dissipation for multiple electrical components in a housing. In such an application, often one of the components generates more heat than other components or generates heat at a temperature that is higher than the temperature of other components served by the heat sink such that its operating temperature is higher than one or more other components coupled to the heat sink. Under these operating conditions, there can be heat recirculation where heat generated by a first component operating at a higher temperature is transferred to the heat sink to be dissipated, however, some of the heat is transferred from the heat sink to a second component ostensibly operating at a lower temperature thereby undesirably raising the operating temperature of the second component.
Disk drives have been a limiting factor in the thermal rating of an industrial computer. A disk drive usually reaches its upper limit operating temperature rating before other electric components reach their respective upper limit operating temperature within an enclosure housing an industrial computer.